1. Field of the Invention
The present invention relates to a blood-pressure measuring apparatus which measures a blood pressure of a living subject, and an inferior-and-superior-limb blood-pressure-index measuring apparatus which measures an inferior-and-superior-limb blood-pressure index of a living subject.
2. Related Art Statement
A blood pressure of a living subject can be measured using an inflatable cuff which is wound around a portion of the subject, such as an upper or an ankle. For example, there are known a Korotkoff-sound blood-pressure measuring apparatus which determines, as a systolic and a diastolic blood pressure of a living subject, respective pressures of a cuff at respective times when the first and last Korotkoff sounds occur during decreasing of the cuff pressure, and an oscillometric blood-pressure measuring apparatus which determines a systolic and a diastolic blood pressure of a living subject, based on change of respective amplitudes of respective pulses of a pulse wave detected during changing of pressure of a cuff.
Meanwhile, a body temperature of a peripheral portion of a living subject is lower than that of a central portion of the same. Therefore, an artery of the peripheral portion of the subject more contracts than that of the central portion of the same, under influence of the lower body temperature. Thus, when a blood pressure of the subject is measured using a cuff that is wound around the peripheral portion, the accuracy of measurement of the blood pressure is not so high. In particular, when an inferior-and-superior-limb blood-pressure index, i.e., the ratio of a superior-limb blood pressure to an inferior-limb blood pressure or the ratio of an inferior-limb blood pressure to a superior-limb blood pressure is measured to diagnose arteriostenosis, a cuff is wound around, e.g. an ankle to measure a blood pressure of the ankle. Thus, the accuracy of measurement of the ankle blood pressure or the inferior-and-superior-limb blood-pressure index obtained therefrom may be lowered by the influence of temperature of the ankle or the leg.
It is therefore an object of the present invention to provide a blood-pressure measuring apparatus or an inferior-and-superior-limb blood-pressure-index measuring apparatus that can measure a reliable blood pressure of a living subject even when a cuff is worn on a peripheral portion of the subject.
The above object has been achieved by the present invention. According to a first aspect of the present invention, there is provided an apparatus for measuring a blood pressure of a living subject, comprising an inflatable cuff which has an inside surface adapted to contact a body surface of the subject and an outside surface exposed to an ambient air, and which is adapted to be wound around a portion of the subject to press the portion of the subject; a first temperature sensor which is provided in the inside surface of the cuff and detects, in a state in which the cuff is wound around the portion of the subject, a temperature of the portion of the subject; and a display device which displays the temperature of the portion of the subject, detected by the first temperature sensor.
According to this aspect, the first temperature sensor is provided in the inside surface of the cuff wound around the portion of the living subject, and the display device displays the temperature of the portion of the subject detected by the first temperature sensor. Since an operator such as a doctor can recognize the temperature of the portion of the subject around which the cuff used for the measurement of blood pressure is wound, the operator can easily judge whether the blood pressure measured using the cuff is reliable or not. If the temperature of the portion of the subject displayed by the display device falls within a pre-determined normal range, the operator can judge that the measured blood pressure is not lowered by the influence of the body temperature. On the other hand, if the temperature of the portion of the subject displayed by the display device does not fall within the normal range, the operator can again operate the present apparatus to obtain a reliable blood-pressure value of the subject.
According to a preferred feature of the first aspect of the present invention, the blood-pressure measuring apparatus further comprises a second temperature sensor which is provided in the outside surface of the cuff and detects, in the state in which the cuff is wound around the portion of the subject, a temperature of the ambient air, and the display device additionally displays the temperature of the ambient air, detected by the second temperature sensor.
According to this feature, the display device displays the temperature of the portion of the subject around which the cuff is wound and additionally displays the temperature of the ambient air. Therefore, if the temperature of the portion of the subject is low, the operator can easily judge whether the temperature of the portion is lowered because of the influence of the temperature of the ambient air, e.g., room temperature.
According to another feature of the first aspect of the present invention, the blood-pressure measuring apparatus further comprises a temperature-difference determining means for determining a difference between the temperature of the portion of the subject detected by the first temperature sensor and the temperature of the ambient air detected by the second temperature sensor, and the display device additionally displays the temperature difference determined by the temperature-difference determining means.
According to this feature, the operator can easily recognize the temperature difference between the temperature of the portion of the subject around which the cuff is wound and the temperature of the ambient air. Therefore, if the temperature of the portion of the subject is low, the operator can easily take a treatment or an action against the low temperature. More specifically described, if the temperature of the portion of the subject is low and the above-indicated temperature difference is considerably small, the operator can raise the room temperature; and if the temperature of the portion of the subject is low and the temperature difference is considerably large, the operator can positively raise the temperature of the portion of the subject by wearing a cloth on the portion or giving a massage to the portion.
According to another feature of the first aspect of the present invention, the blood-pressure measuring apparatus further comprises a judging means for judging whether the temperature difference determined by the temperature-difference determining means is greater than a reference value; and an output device which outputs information indicating a judgment made by the judging means.
According to this feature, the output device outputs the information, such as a message in the form of a sound or an image, or a printed matter. From the information, the operator can easily recognize the temperature difference between the temperature of the portion of the subject around which the cuff is wound and the temperature of the ambient air. Therefore, if the temperature of the portion of the subject is low, the operator can easily take a treatment or an action against the low temperature.
According to a second aspect of the present invention, there is provided an apparatus for measuring an inferior-and-superior-limb blood-pressure index of a living subject, comprising an inferior-limb blood-pressure measuring device which includes an inferior-limb cuff adapted to be wound around an inferior limb of the subject and measures a blood pressure of the inferior limb; a superior-limb blood-pressure measuring device which includes a superior-limb cuff adapted to be wound around a superior limb of the subject and measures a blood pressure of the superior limb; an inferior-and-superior-limb blood-pressure-index determining means for determining the inferior-and-superior-limb blood-pressure index of the subject, based on the blood pressure of the inferior limb measured by the inferior-limb blood-pressure measuring device and the blood pressure of the superior limb measured by the superior-limb blood-pressure measuring device; a display device which displays the inferior-and-superior-limb blood-pressure index of the subject determined by the inferior-and-superior-limb blood-pressure-index determining means; an inferior-limb temperature measuring device which measures a temperature of the inferior limb of the subject; a superior-limb temperature measuring device which measures a temperature of the superior limb of the subject; and a display control means for controlling the display device to simultaneously display the temperature of the inferior limb of the subject measured by the inferior-limb temperature measuring device and the temperature of the superior limb of the subject measured by the superior-limb temperature measuring device.
According to this aspect, the display control means controls the display device to simultaneously display the temperature of the inferior limb of the subject measured by the inferior-limb temperature measuring device and the temperature of the superior limb of the subject measured by the superior-limb temperature measuring device. Since the operator can recognize the respective temperatures of the superior and inferior limbs around which the respective cuffs are wound for the blood-pressure measurement, the operator can easily judge whether the respective blood-pressure values measured by the superior-limb blood-pressure measuring device and the inferior-limb blood-pressure measuring device are reliable. For example, if the temperature of the inferior limb is much lower than that of the superior limb, the operator can judge that the accuracy of the blood pressure of the inferior limb is low because of the influence of the low temperature of the inferior limb. In this case, the operator can try to measure a reliable blood-pressure value after raising the temperature of the inferior limb.
According to a third aspect of the present invention, there is provided an apparatus for measuring an inferior-and-superior-limb blood-pressure index of a living subject, comprising an inferior-limb blood-pressure measuring device which includes an inferior-limb cuff adapted to be wound around an inferior limb of the subject and measures a blood pressure of the inferior limb; a superior-limb blood-pressure measuring device which includes a superior-limb cuff adapted to be wound around a superior limb of the subject and measures a blood pressure of the superior limb; an inferior-and-superior-limb blood-pressure-index determining means for determining the inferior-and-superior-limb blood-pressure index of the subject, based on the blood pressure of the inferior limb measured by the inferior-limb blood-pressure measuring device and the blood pressure of the superior limb measured by the superior-limb blood-pressure measuring device; a display device which displays the inferior-and-superior-limb blood-pressure index of the subject determined by the inferior-and-superior-limb blood-pressure-index determining means; an inferior-limb temperature measuring device which measures a temperature of the inferior limb of the subject; a superior-limb temperature measuring device which measures a temperature of the superior limb of the subject; a temperature-difference determining means for determining a difference between the temperature of the inferior limb of the subject measured by the inferior-limb temperature measuring device and the temperature of the superior limb of the subject measured by the superior-limb temperature measuring device; and an output device which outputs, when the temperature difference determined by the temperature-difference determining means is greater than a reference value, information related to a fact that the temperature difference is greater than the reference value.
According to this aspect, if the difference between the respective temperatures of the inferior and superior limbs, determined by the temperature-difference determining means, is greater than the reference value, the output device outputs information related to a fact that the temperature difference is greater than the reference value. Thus, the operator can easily judge whether the respective blood-pressure values measured by the superior-limb blood-pressure measuring device and the inferior-limb blood-pressure measuring device are reliable. For example, if the temperature of the inferior limb is much lower than that of the superior limb, the operator can judge that the accuracy of the blood pressure of the inferior limb is low because of the influence of the low temperature of the inferior limb. In this case, the operator can try to measure a reliable blood-pressure value after raising the temperature of the inferior limb.
According to a preferred feature of the second or third aspect of the present invention, the inferior-limb temperature measuring device comprises an inferior-limb temperature sensor which is provided in an inside surface of the inferior-limb cuff and is adapted to contact a skin of the inferior limb of the subject so as to measure the temperature of the inferior limb of the subject.
According to this feature, when the inferior-limb cuff is worn on the inferior limb, the inferior-limb temperature sensor is simultaneously worn on the inferior limb to measure the temperature of the inferior limb.
According to another feature of the second or third aspect of the present invention, the inferior-and-superior-limb blood-pressure-index measuring apparatus further comprises an ambient-air temperature sensor which is provided in an outside surface of the inferior-limb cuff and detects, in the state in which the inferior-limb cuff is wound around the inferior limb of the subject, a temperature of the ambient air.
According to this feature, when the inferior-limb cuff is worn on the inferior limb, the ambient-air temperature sensor is simultaneously worn on the inferior limb to measure the temperature of the ambient air.
According to another feature of the second or third aspect of the present invention, the superior-limb temperature measuring device comprises a superior-limb temperature sensor which is provided in an inside surface of the superior-limb cuff and is adapted to contact a skin of the superior limb of the subject so as to measure the temperature of the superior limb of the subject.
According to this feature, when the superior-limb cuff is worn on the superior limb, the superior-limb temperature sensor is simultaneously worn on the superior limb to measure the temperature of the superior limb.